Singapore studies role of oral HCQ & throat spray in reducing COVID-19 spread Singapore studies role of oral HCQ & throat spray in reducing COVID-19 spread 26 April 2021 | News Preventive regimen shown to be effective in reducing COVID-19 transmission in a large-scale randomised controlled trial conducted among healthy migrant workers in Singapore Image credit- NUHS A team of clinician-scientists from the National University Hospital (NUH); NUS Yong Loo Lin School of Medicine (NUS Medicine); NUS Saw Swee Hock School of Public Health; National University Cancer Institute, Singapore; and National University Heart Centre, Singapore has found that oral hydroxychloroquine (HCQ) and povidone-iodine throat spray were effective in reducing the spread of COVID-19 infection in high transmission settings.